From what I've seen, mixing gymnastic training with running and endurance would probably work. Maybe you can set up a few practice obsticles for specific moves, like some vertical and horizontal bars. Or you can find something equivelant.

Parkour is like malaria, it needs a specific carrier organism to spread, in this case instead of Anopheles gambiae, liberal arts students with self woven-woollen beanies seem to be the first host . Must have something to do with not washing one's hair.

heya i do parkour, i recommend just going on youtube n checking out the basic techniques and practicing them dilligently on a ground level for a year or so then progress to higher, more dangerous obstacles if you're prepared for it :) learning how to land and roll is paramount so that should definetly be a priority...

There is a lot of specialized conditioning for it. Go peruse youtube user UrbanCurrent for some excellent examples. The general idea is to condition the body and find the most efficient ways of negotiating obstacles. This includes an emphasis on landing softly to protect the joints.

As always, its best to have a well qualified instructor. Try getting in touch with nearby parkour groups (even if they're in a different country if necessary) and ask them for help - it usually has a fairly open and friendly culture with people who are eager to help.